German Published Patent Application 10 2004 010135 describes a device for energizing an ignition output stage using a firing current from an energy reserve. A voltage regulator, whose function is to adjust a voltage at the at least one voltage output stage to a predefined value, is provided between the energy reserve and the ignition output stage. The voltage regulator is configured in an ASIC.
FIG. 6 shows a block diagram of a voltage pre-regulator for ignition output stages in accordance with a conventional system. A device 600 is shown that is designed to supply a firing current to an ignition output stage 102. The ignition output stage 102 is designed to trigger a firing pellet 104. The device 600 is connected to an energy reserve 106 and to a microcontroller 108. The device 600 has an N-channel MOSFET 120 for supplying the firing current. The firing current is supplied by a source terminal of the N-channel MOSFET 120. A drain terminal of the N-channel MOSFET 120 is connected via a diode 128 to the energy reserve 106. A gate voltage of the N-channel MOSFET 120 is supplied by a capacitor 122 via an ASIC 624. ASIC 624 has a charge pump 634 and two transistor circuits. Microcontroller 108 is designed to supply an ON/OFF signal to ASIC 624 in order to interrupt a supplying of the firing current. In addition, microcontroller 108 is designed to supply a “firing” signal to ignition output stage 102. A connection between device 624 and the source of MOSFET 120 is not shown in FIG. 6.
Thus, the functions for supplying the firing current are integrated in the transistor 120 and the ASIC 624. The ASIC 624 is designed for regulating the external N-channel MOSFET transistor 120 in a source follower architecture. In this context, the ASIC 624 keeps the gate terminal of the transistor 120 at a predefined voltage, respectively regulates it thereto. The source terminal follows the gate (VSOURCE=VGATE−VGS(th)), and the firing current regulated by the ignition output stages flows over the MOSFET transistor 120. The entire ASIC 624 is powered by a charge pump 634 and the external capacitor 122. The charge pump 634 ensures that the gate voltage of the MOSFET transistor 120 holds its value, even in the case of a sudden dip in the power supply 106 (energy reserve voltage) during firing, so that the MOSFET transistor 120 is able to be switched through at the lowest possible resistance RDS(ON).